1. FIELD OF THE INVENTION
The present invention relates to hard butter prepared by using a vegetable oil or fat as the raw material.
More particularly, the present invention relates to a hard butter prepared from a selective hydrogenation-isomerization product of a palm olein and a vegetable oil or fat other than palm oil. The term "palm olein" used herein is intended to denote the fraction obtained by removing higher melting components such as tri-saturated glycerides from palm oil by fractionation.
2. DESCRIPTION OF PRIOR ARTS
As the conventional process for preparing a hard butter by merely hydrogenating a palm olein, there can be mentioned a process disclosed in the laid-open specification of Japanese patent application No. 96760/73. A hard butter obtained by merely hydrogenating a palm olein is defective in that it lacks a good mouth-melting property inherent in ordinary hard butters and since large quantities of solid fats are left unmolten at temperatures higher than the body temperature, when this butter is put into the mouth, it gives an unpleasant touch or feel resembling that of wax. The phenomenon that solid fats are left unmolten at temperatures higher than the body temperature is not desirable for hard butters. The reason why a product obtained by merely hydrogenating a palm olein is inferior in the mouth-melting property is that since the contents of unsaturated acids, especially polyene-acids, based on the total constituent fatty acids in the palm olein are low and the contents of saturated acids are as high as 30 to 45% by weight as a whole, tri-saturated glycerides are formed by hydrogenation, and high-melting-point glycerides are formed by trans-isomerization of unsaturated acids.
The specification of U.S. Pat. No. 3,199,984 discloses a process for preparing a hard butter by hydrogenating a vegetable oil or fat other than palm oil, and the specification of British Pat. No. 1,214,321 discloses a process for preparing a hard butter by hydrogenating a vegetable oil or fat and fractionating the resulting hydrogenation product. When hard butters prepared according to these known processes are used for preparation of chocolates, since they are insufficient in their compatibility with cacao butter, a drastic decrease of the melting point is caused when they are mixed with cacao butter, resulting in insufficient hardness and insufficient heat resistance. Moreover, blooming is often caused depending on the kind of the starting oil or fat.